I’m creating a proof-of-concept with ionic. Obviously for me and my clients it is obviously very important that the product is stable. I have no experience with ionic but it seems like it would be a nice solution to the problems that we have (where appgyver seems to fail). The question that I have to ask is which ionic to use? Is there a significant difference between the stability of 1.3 and 2 beta x?

This really depends on your needs.
As we see things. Ionic 1x is feature complete and is in stability mode right now. No new features will be added, but if there are huge bugs, we’ll fix them.

That being said, it’s stable, well tested, and used quite a lot.

Our focus on development is push V2 forward. While it’s still in development, there are less breaking changes every release. Most of the times we break things, we do provide detailed upgrade instructions to help people along.

So, if you need to ship something in a week or 2, use ionic1
But if not, and you don’t mind checking the change log every now and then, give V2 a shot.